Eligibility

This section clarifies who is eligible to attempt each of the puzzle sets.

Any competitor, official or unofficial, who served as a puzzle author, co-author, reviewer or tester (hereinafter commonly as: “Author”) for a puzzle set is ineligible to attempt the puzzle set they have contributed to. The list of the names of all these people has been listed in the original announcement.

Any competitor, official or unofficial, who has an “Author” in their team, is ineligible to attempt the set of that “Author”.

Any competitor, official or unofficial, who has an “Author” as their team captain or other personnel is ineligible to attempt the set of that “Author”.

Any competitor, official or unofficial, who has an “Author” as their compatriot (assuming standard nationality rules) is ineligible to attempt the set of that “Author”.

In case any competitor is rendered ineligible for at least two of the sets, a case by case review is required by the Organising Committee to determine if and how that competitor can still compete in three sets.

Rules

Competitors, who by the means above, are eligible to attempt only three of the puzzle sets, will complete those three sets and skip the one they are ineligible to attempt.

Teams whose members are eligible to attempt all four puzzle sets are line up themselves so that each member of the team skips a different puzzle set.

Teams of four competitors will therefore line up themselves so that each of the puzzle set is attempted by exactly three of them, while each of the puzzle sets is skipped by exactly one of them.

Teams of less than four competitors are still required to ensure that they all skip a different puzzle set.

Teams are required to communicate their decisions to the Organising Committee prior to Round 1 of the Championship starts. The Organising Committee will not publish the decisions of any of the teams before that deadline, to avoid influencing other teams in their own decisions.

The decision is made by the members of the team. Given the timing, teams are welcome to study the Instruction Booklet that will, as usual, be published ahead of the event and arrive at their decision knowing the exact details about the puzzle types of each of the puzzle sets.

Rationale

It is important to note about the eventual system described above that teams who are not affiliated with any of the “Authors” may actually be getting a slight tactical advantage by being given the option to determine which of them will attempt which of the sets, whereas the author teams do not get such a choice, they obviously need to work with the “other” three sets.

This will hopefully eliminate any concerns that authors or their teams are gaining any (real or perceived) advantage by the introduction of this “80 puzzles” system, because they clearly do not. Authors and (when already known) their teams have been directly contacted and communicated about the possibility that they may be at a slight disadvantage as a result.

It is also a nice property of the proposed system that authors aside, all their sets will be attempted by an equal, or almost equal number of competitors. One result of this is that the official team results will very likely include an equal number of attempts over all four puzzle sets (assuming that only four official teams will be “Author”-affiliated).

There were a few other ideas on the table which have been ultimately dismissed.

One idea was to have all competitors attempt all four sets who would otherwise be eligible to do so, and then have a way to transform those four scores into just three. This could have been achieved in a balanced way (e.g. to multiply all of them by 75%) or in a way that would explicitly favour these non-author teams (e.g. to pick the best 3 results out of the 4, thereby effectively providing them with a wildcard option “you can screw up one round for free”). One of the reasons this idea was dismissed, however, is that “Authors” and their teams/compatriots would then have an hour of resting time while everybody else is competing, and it seems extremely hard, if not impossible, to weigh or quantify whether any possible adjustment on the scores would fairly balance the advantage they may get just by having a more relaxed schedule. Another argument against this scheme is that according to our data evaluation, such a wildcard option was found to provide more benefit to less consistent solvers than to more consistent ones, and that's hardly a good incentive to introduce.

Another set of ideas were discussed around how to determine which competitor skips which of the sets (wherever there is a choice). It could have been decided in a completely centralised way, but then any such decision would have probably been seen as rather arbitrary and therefore questionable, so we did not go for it. Alternatively, we could have said that every competitor is completely free in picking their skip set – while that may have been a popular option at first glance, it has the potential to result in one of the sets being skipped by a significant majority of the competitors for whatever (probably mostly perception-driven) reasons, and that not only comes down badly on the author team of that set, it it also makes any scoring system more unstable.

Notes

This document was sent for review to a couple of people a few days before its public appearance. Feedbacks, suggestions and remarks were received and, where applicable, incorporated.